Construction and control of cold rolling mills



Jan. 8, 1957 $ENDZ|M|R 2,776,586

CONSTRUCTION AND CONTROL OF COLD ROLLING MILLS Filed June 10, 1948 3Sheets-Sheet l 7'0 744 4; (80 71/1. f 18 W I] I AfvM 0/4 -Sl/PPL YINVENTOR. 7205052 SE/VDZ/M/IT.

ATTORNEYS? Jan; 8, 1957 T. SENDZlMIR r 2,776,536

CONSTRUCTION AND CONTROL OF COLD ROLLING MILLS Filed June 10, 1948 sSheet-Sheet 2 INVEN TOR. 73aEusz $NDZIMI$Z ATTORNEYS.

Jan. 8, 1957 T. SENDZIMIR I 2,776,586

CONSTRUCTION AND CONTROL OF GOLD ROLLING MILLS Filed June 10, 1948 5Sheets-Sheet 3 BTW W I i Q 5; 4

Ill/III I I E6. 8. INVENTOR.

QZZMYQM ATTORNEYS.

United States Patent CONSTRUCTION AND CONTROL OF COLD ROLLING MILLSTadeusz Sendzimir, Middletown, Ohio, assignor to Armzen Company,Middletown, Ohio, a corporation of Delaware Application June 10, 1948,Serial No. 32,215

3 Claims. (Cl. so-ss My invention relates to cold rolling mills of thegeneral type shown in my United States Letters Patent Nos. 2,169,711 and2,187,250.

The principal objects of this invention are to provide improvements inthe construction of mills of this type such that better control is hadof the working operation and better control of the contour of the workpiece, both objects being attained by structural changes and arrangements of parts as will be described herein. These and other objects ofthe invention which will be set forth or will be apparent to one skilledin the art upon reading these specifications I accomplish by theaforesaid structural changes and modifications of which I shall nowdescribe certain exemplary embodiments. Reference is made to theaccompanying drawings wherein:

Figure 1 is a partial cross-sectional view of one type of millarrangement showing the directions of components of force.

Figure 2 is a partial cross-sectional view of a mill arrangementemploying staggered backing elements, and including a diagrammaticshowing of a mechanism for mill release.

Figure 3 is a partial cross-sectional view of another mill arrangementemploying staggered backing elements and incorporating a releasemechanism.

Figure 4 is a partial cross-sectional view of a mill arrangement whichis modified over those hereinabove referred to, and which alsoillustrates certain means for applying lubricant and for wiping therolls, which means are applicable to all of the forms of mill shownherein.

Figure 5 is a diagrammatic elevational view of a work roll and anintermediate roll with a work piece shown in section, the drawingillustrating a means for preventing over-rolling at the edges of thestrip.

Figure 6 is a similar view showing another roll arrangement for the samepurpose.

Figure 7 is a diagrammatic view of a pair of work rolls and a pair ofintermediate rolls showing another form of contour control means.

Figure 8 is an isometric view of a mill housing so shaped as to controlroll deflection.

Figure 9 is an elevational view with parts in section of a drivenintermediate roll, coupling means, thrust means, and a roll hold-upmechanism.

Figure 10 is a longitudinal section of a bearing and saddle assemblyshowing means for controlling the flow of lubricant.

Figure 11 is a longitudinal sectional view of another arrangement ofbacking bearings and saddles provided with a positive sealing means andmeans for the separate circulation of lubricant to and through thesebearings.

My invention relates to rolling mills of the general type of those setforth in my patents referred to above, in which mills small diameter andrelatively slender work rolls are supported by one or more sets ofintermediate rolls which in turn are supported by caster elementsjournaled on shafts having a bearing against beams extendingtransversely of the mill. Such mills are especial Patented Jars. 8,195%? 1y useful in making carefully controlled or very heavy reductionsin metallic strips, by which is meant here Work pieces of indefinitelength irrespective of their specific width.

In such mills the direction of pressure on the final backing casters isat an angle to the roll pressure at the work rolls, which roll pressureis usually in the vertical direction. In a mill through which the strippasses horizontally, only the vertical component of the rolling pressureis useful in the rolling operation, although the horizontal component isof necessity present, because of the angular position of the backingcasters.

On a conventional four-high mill, where the backing is in the samedirection as the roll pressure, for each 1000 tons of roll pressure, themain bearings have to withstand only 1000 tons. As distinguished fromthis, in a cluster mill where each work roll is backed in a non-verticaldirection by two backing rolls, each one of the backing rolls will haveto withstand usually from 60 to 70 percent of the total roll pressure.Thus the two backing rolls on either side of the work piece will have towithstand a total pressure which is about to percent of the verticalrolling pressure. It will be clear that more bearing capacity has to bebuilt into such mills.

This makes it clear why in cluster mills it is advantageous so to placethe backing elements that their corresponding pressures do not lie atangles too close to the horizontal, and also why, when more than twobacking elements are employed for each Work roll it is advantageous tohave the bearing pressures distributed as evenly as possible between allof the backing elements to insure that their bearings have a long life.

In mills of my type, however, as set forth in the copending applicationof myself and John E. Eckert, Serial No. 485,750 and now Patent No.2,479,974, granted August 23, 1949, filed May 5, 1943 and entitled TheDesign and Construction of Rolling Mills, after long experimentationwith various roll arrangements, an advantage has been found in doingexactly the opposite, i. e. disposing outer ones of the caster elementsso that their lines of pressure come as close to the horizontal aspossible, taking into account the accessibility of the mill. In such anarrangement the most inclined caster elements will take the biggestshare of the load and those caster elements having lines of pressurecloser to the vertical will take a smaller part of the load.

In Figure 1, l have illustrated in section a portion of a millcomprising a pair of work rolls 1, a set of first intermediate rolls 2,a second set of intermediate rolls of which the three upper ones, marked3, 3A and 3B are shown, and a series of upper casters marked 7, 8, 9 and10. The primary rolling pressure is indicated by an arrow marked P. Thebacking casters 7 and 10 sus- 'tain the largest components A and D ofthe roll pressure P whereas the backing casters 8 and 9 sustain thesmallest components l3 and C. Components A and D are closer to thehorizontal, whereas B and C lie more nearly in the vertical directionand are closer to the direction of the primary rolling pressure P. Thosebacking casters which sustain the smaller load may be made of lesserdiameter as illustrated in Figure 4 of this application, or they may bestaggered as illustrated in Figure 2 hereof, in ways commensurate withthe loads they have to bear.

It has been found in applying these principles, which appearparadoxical, that they permit a geometrical arrangement of the mill inwhich a great reduction in the diameter of the Work rolls for a givennumber and diameter of ultimate backing casters becomes possible. Inthis Way a more accurate mill is provided, and also one in which thework roll pressure is smaller and therefore the total pressure on thebacking caster elements 3 becomes less in spite of their unfavorableangular position.

The relatively high share of the rolling pressure which is sustained bythose backing casters most inclined from the vertical means that theintermediate rolls which are in working contact with them also carry agreater share of the load than the ccn er intermediate roll of the samegroup, or other intermediate rolls of the same group disposed indirections closer to the vertical. But at the same time the outerintermediate rolls in the most inclined positions can be made of verysubstantially greater diameter than other intermediate rolls; andanother advantage of the arrangement is that if the most inclined outerintermediate rolls are employed as driving spindles, they are capable oftransmitting heavier torques to the mill.

As set forth in the copending application Serial No. 485,750 now Patent#2,479,974 referred to above, an advantage is obtained by applying thedriving torque to intermediate rolls, whether they be the firstintermediate rolls 2 in Figure 1 or the outer intermediates 3, 3A and3B, rather than directly to the Work rolls as was previously done, sincethe very slender work rolls in these mills have low torque transmittingcapacity. Thus, there is a net gain of several times the maximum torquethat can conveniently be transmitted, because the number of rolls whichcarry the torque can be at least doubled, and their diameter will be atleast about 2 /2 times larger than the diameter of the work rolls.

In mills having more than one group of intermediate rolls, anarrangement involving unequal distributor-l of loads to the differentrolls, makes it possible to apply the drive to the four outside rolls inthe group of six largest intermediate rolls, such as the group 3, 3A and3B of Figure l. The rolls 3A and 313 have the largest angularity to therolling pressure P; and it is not necessary to complicate the drive byapplying torque to all six or more of the outside intermediate rolls.Since the rolls of greater angularity carry the larger load, theytherefore can alone transmit a sufficient torque by friction to the nextseries of inermediate rolls such as the rolls 2 in Figure 1, and fromthere the working rolls 1. In such an arrangement marked advantage issecured not only from the fact that the driving spindles may berelatively large, but also from the fact that, because of the largedistance between the driven intermediate rolls, a pinion stand may beused which has a relatively low tooth pressure.

in using mills of this type, it has been found in operation that minutedeflections tend to occur in the roll assembly and housings, especiallywhen heavy reductions are made and the operating loads are high. Thesedeflections permit Work rolls 1 to deflect more in their centralportions than near the edges of the strip. This causes the stretching orelongation of the metal strip being rolled to be uneven unlesscompensation is made for the deflections. The unevenness of stripelongation usually manifests itself in wavy edges of the strip caused byover rolling when the slender work rolls bend over the edges of thestrip.

To overcome this difliculty, the present invention includes means toinsure that the elongation of the strip being rolled will be uniformacross its width. One aspect of this improvement lies in contouring theintermediate mill rolls, such as the rolls 2 in Figures 5, 6 and 7. Thiscontouring consists of a taper relief which is shown greatly exaggeratedat 23 in Figures and 6. This taper relief may be formed on or near theends of the work rolls or any series of intermediate rolls at thepositions of the edges of the strip S which is being rolled. It ispreferred to form it on the ends of the first series of intermediaterolls by reason of their flexibility. The taper relief is slight, butsuflicient to prevent the work rolls from bending at their ends over theedges of the strip so as to prevent edge over-rolling. Thus the flatportion of the contoured intermediate rolls 2 is usually narrower thanthe strip being rolled, so that the taper rclief starts slightly insidethe strip edge on the rolls as illustrated in Figures 5, 6 and 7. It hasalso been found beneficial to employ crown on one or more of the rolls,and particularly on the work rolls when used in combination withtaper-relieved intermediate rolls. This minimizes the amount of tapernecessary. Crown on a work roll is illustrated in an exaggerated form inFigure 6, where the Work roll 1A is shown as having a crown. In actualpractice the amount of crown will be restricted to several thousandthsof an inch.

It is not necessary to relieve all rolls of any given set. The taperrelief, which usually is also no more than several thousandths of aninch, may be ground on one or both ends of one or more rolls, or onopposite ends of different rolls in a set. When one or more rolls aretapered on or near both ends, as in Figures 5 and 6, and remain in fixedpositions in the mill, the relieving action at the strip edges will begood only over a small range of strip widths rolled in the mill. If,however, the relieved rolls can be made axially adjustable, they maythen be provided with means for axially shifting their positions and awide range of strip widths can be rolled on them. If means for axiallyshifting the roll positions is provided, the rolls so shifted may stillbe tapered on or near both ends if desired, but it becomes necessaryonly to taper alternate rolls on opposite ends, opposite rolls onopposite ends, or rolls of different sets on opposite ends. The meansfor axial adjustment may be applied to work rolls or to any set ofintermediate rolls having the taper contours described above.

In Figure 7 there is illustrated a roll assembly comprising Work rolls1, and intermediate rolls 2A and 2B. The roll 2A has a taper relief ator adjacent as at 23A while the intermediate roll 2B has a taper reliefat or adjacent its opposite end as at 238. The intermediate roll 2A isshown as provided with a thrust bearing 27' and connected thereby to anon-rotative link 28 which, in turn, is connected to a rack 29. A gearwheel or pinion 30 has teeth meshing with the rack and with a worm 31 onthe drive shaft of an electric motor 32 or other prime mover forshifting the axial position of the roll. The intermediate roll 23 willbe connected through a thrust bearing 2713 to a similar mechanicalarrangement for shifting its axial position, preferably equally and inthe opposite direction. By these means the taper reliefs 23A and 23B onor near the opposite ends of thc illustrated intermediate rolls may bemade substantially to coincide with the edge portions of a wide range ofstrips being rolled in the mill. The axial adjustment which has beendescribed can also be accomplished satisfactorily by hydraulic and othermeans.

The regular deflections under load in the mill housing itself aregreatest at a point corresponding to the center of the strip beingrolled, since this point is farthest distant from the mill columns. Oneof the objects of the invention is to counteract this, and provide meanswhich insure that the mill will roll a flat strip irrespective of load.To accomplish this, a special housing structure is provided whichincludes weakened side portions which will have a greater ability todeflect at areas corresponding to the side edges of the strip, and sointroduce an artificial, supplementary deflection which will make thetotal or resultant deflection at the work rolls uniform over the entirewidth of the strip.

In Figure 8 there is illustrated the housing for one of my mills. Thestrip being rolled enters and leaves the mill through windows W, andthese windows together with the central space of the housing in whichthe work rolls and other operating elements are mounted, divide thehousing into columns 40 and beams 40A, as will readily be understood.The compensation described above may be attained by suitably taperingthe edge portions of the beams 40A as illustrated at 39 and 39Aequidistant from the columns 40. When this is done,

thewassemblies of backing casters 7 andv in Figure 1, when mounted inthe mill housing, will deflect most at the center of the strip, whereasthe assemblies of backing casters 8 and 9 of Figure 1 will deflect mostnear the edges of the strip.

: Since one established contour on the rolls themselves in a given mill,such as has-been described in connection with Figures 5, 6 and 7, maybegood only for a certain roll pressure and a certain given widthandreduction of the metal, the benefits of a specially shaped housingacting as above described have herein been combined with contour rollsand means for their axial adjustment to permit greater versatility forrolling strips of a wide range of widths and hardnesses and for takingvarious reductions of any desired percentages. In mills of this typehitherto described, as in the copending application Serial No. 485,750and now Patent No.1 2,479 ,,974 referred to above, the backing castershave been journaled on shafts with eccentric portions, which in turn aremounted in holding members or saddles lying against the mill housingbeams. According to the present invention a more effective constructionhas been produced by providing plain cylindrical shafts for the castersand employing eccentric discs keyed to. them. In this way the diameterof the eccentric element becomes greater, providing more room for theinstallation of roller bearings which do away with static friction whenrotating the shafts under load in order to set the roll pass screw-down.Another advantage is that the saddles themselves do not need to besplit; and the backing caster shafts with their eccentric discs andsaddles and the casters themselves, form subassernblies that may becarried as spare parts for exchange in case of breakdowns.

Referring to Figure l, the shafts 5 are provided with roller bearings,such as 11, having rollers engaging between eccentric discs 6 keyedtosaid shafts 5 by keys 64, and saddle elements 4, which engage inappropriate grooves or recesses in the mill housing beams, 40A.

A further advantage is attained by providing a common locking device foreach saddle and caster assembly, which device may be operated from oneend of the mill. This may comprise a fixed bar 36 (Figure l) affixed tothe mill housing, and a slidable, tapered bar 12 having a toothed endsectionwhichis motivated by a worm 13. Longitudinal movement of, themovable tapered bar 12 will force each saddle against a fixed stop 36Aon the housing beam.

It will be clear from the foregoing description that if the discs 6,which are keyed to the shafts 5 and 6 are mounted by means of the rollerbearings in the saddles, are eccentric in form, a rotation of the shafts5 will effect the screw-down of the mill. In such a mill it is possiblethat while rolling, an unusually high load may accidentally be appliedto the mill bearings, and might be beyond their capacity. To eliminatethe chance of failure and to protect the casters as well as the rolls, ayieldable feature is provided in the arrangement of backing elements orcasters assembly, whichghowever, will hold the backing elements rigidlyin position up to a predetermined roll pressure.

This may be accomplished by splitting one or more of the bearing shafts5 into two parts 5A and 5B as illustrated in Figure 2 along a planelying substantially normalto the"rolling pressure, leaving within theshaft a flat concavity 21 deep enough to provide for an adequate, safecollapsing distance. Fluid pressure is applied to the cavity 21 urgingthe two shaft sections 5A and 5B in Figure 2 apart and pressingthemagainst the bores of the casters 7 and eccentric rings 6. Elasticseals marked 22 prevent oil leakage, but are of resilient nature so asto collapse when the rolling pressure forces the shaft sections SAand 5Btogether. Whenever the predetermined pressure setting of an overloadvalvewhich isincorporated in the system is exceeded, owing to a suddensurge of load on the casters, the overload valve of the pressure systemwill give way, permitting the two parts of the shaft to approach eachother and thus relieve the casters and all pressure bearing elements ofthe mill.

While a yieldable protection feature has been set forth as embodied inthe bearing shaft 5, it may also be employed on any other bearingelement or combination of them within the scope of this invention. Evenparts of the mill housing can in a similar fashion be made to yieldunder excess load to protect the loaded mill parts from damage, Withinthe scope of these disclosures.

Yet another type of relief mechanism, as heretofore described inapplication Serial No. 485,750, now Patent #2,479,974, may be employedas shown in Figure 3. Here the work rolls 1 rest upon two intermediaterolls 2 which, in turn, rest upon three sets of staggered casters 41,42, and 43. These casters or bearings are rotatably mounted on theshafts 5 which in this mill are mounted in supports on a single saddleor cradle 44. The cradle has a cylindrical outer surface which iseccentric to the axis of the work roll 1. It is rotatably journaled in asemi-cylindrical recess in the beam of the mill housing; and it may begiven an anti-frictional mounting by means of a series of rollers 46. Atone side of the beam there is provided a fixed stop 47, while at theother side a lever or series of levers 48 are pivoted on bearings 49afi'ixed to the mill beam. One end of the lever or levers engages a slotformed in the cradle 44, while at the other end there is provided someconstant force means such as a compression spring 50 engaged between thelever and a socket 51 on the beam of the housing. The effect of thespring 549 is to force the cradle 44 in a clockwise direction againstthe stop 47; and the force exerted by the springs is adjusted tocounteract the expected or desired rolling pressures. Up to a desiredpredetermined rolling pressure for which the springs 50 are adjusted,the mill will be rigid, because the cradle 44 will be held against thefixed stop 47. But when the working rolls encounter an obstruction andthe roll separating force is suddenly increased beyond thatpredetermined value, the cradle 44 will rock in a counterclockwisedirection against the force exerted by the springs. This is due to theeccentricity of the cradle surface relative to the work'rolls, describedabove.

The same mechanism may be used for screw-down purposes by substitutingan adjustable stop in the place of the fixed stop 47 so that the rollingposition of the cradle 44 can be changed to vary the operating positionof the work rolls. It should be understood that other means than thecompression springs 50 may be used for a constant force means, such asfluid pressure cylinders and the like.

A further advantage of the roll arrangement shown in Figures 1 and 2lies in the simplicity of the provision of the screw-down control. Sincethe operating positions of the work rolls will be controlled by changingthe anguluar position of one or more of the backing shafts 5 and theeccentric discs keyed thereto, and since two symmetrically disposedshafts may be selected for screwdown purposes, and are provided withbearings free of static friction on the saddles, it is possible toprovide gear segments 15 in Figures 1 and 2 on the ends of these twoshafts, and engage the teeth of these segments with a double' faced rack(14 in these figures). The rack may be attached to an hydraulic pistonrod 16 connected to the piston 17 of a cylinder 19. A raising orlowering of the piston will control the angular position of both shaftsand hence vary the screw-down of the mill. On wide mills it isadvantageous to provide gear segments, racks and pistons at both ends ofthe shaft, thereby avoiding any inaccuracy which would result from atwisting of the shafts due to torque exerted by a piston at one endthereof.

To operate such a screw-down, use may be made of a known hydrauliccontrol system comprising a follow valve indicated at 18 in Figure 2,connected to the cylinder 19 by tubes 79 and 8d at opposite ends of thecylinder 19. The adjustable element 78 of the follow valve may beoperated directly by a remote control systern by the mill operator. Theother element of the valve is mechanically connected by a linkage 77 tothe piston rod 16 so that it stops the flow of hydraulic fluid as soonas a predetermined screw-down position has been reached. The chiefadvantage of this system is that when, through leakage or other causes,the position of the piston has changed, the valve 18 will automaticallyadd fluid to restore the position set by the operator, within narrowlimits. A pressure relief valve 20 may also be incorporated in thissystem and, assuming lack of friction in the caster and saddle bearingswill provide for relief in the event of a sudden great excess in therolling pressure. ln mills having a cluster arrangement of the rolls, asherein described, each roll is nested or supported by two backing rollsor bearing assemblies parallel to each other. In this way, there can beno cocking of the rolls, i. e. such a change in position as would throwthem out of parallelism. According to this invention, axial freedom ofall non-shiftable roll ends is limited by bearing plates 25 in Figure 9,which may be stationary or rotatable, and may be alfixed to the doors 76of the mill housing. if stationary abutment plates 25 are used, it ispreferable to atfix a rotatable bearing 24 of thrust sustainingcharacter to the roll end. This bearing is mounted in a case 37 which isprovided with a fiat surface abutting against the thrust plate. In thisway doors 76 at the ends of the mill housing will sustain axial thrustsapplied to the rolls during operation, while permitting these rolls toadjust their radial positions. Since it is preferred to support allexcept the work rolls in the upper half of the mill so that they willnot gravitate against the bottom work roll when the screw-down is up,springs 26 in Figure 9, air operated piston rods, or other convenientsustaining and lifting means are, according to this invention, attachedto the case elements 37 which hold the thrust bearings 24 of theserolls.

The driven ends of driven rolls such as the roll 3 of Figure 9 aresimply engaged by sliding them into the coupling ends of spindles 33.They butt against spherical thrust elements 34 in these spindles; andthe spindles transmit the axial thrust to corresponding pinion standbearings (not shown). Rolls mounted in this manner are free to beremoved from the mill upon the opening of the mill doors 76.

The improvements in mill construction and operation herein outlineddepend for their precision on the maintenance of an even temperature ofthe mill elements including all rolls and backing bearings, in spite ofthe heat generated at the line of contact between the strip and the workrolls, between the individual rolls, between the intermediate rolls andthe casters, and within the bearings of the casters. High productionmills may consume several thousand horsepower, a part of which goes intosliding and rolling friction, Any local heating will throw the mill outof line and produce a wavy and inaccurate strip almost immediately.Further, once a local heating has occurred, lubrication is upset, andthe parts expand locally creating higher local pressures, so that thesituation becomes staggeringly worse within a very short time. While ageneral or uniform change of the mill temperature over the whole widthof the strip is of less consequence, it still presents a problem of milladjustment' Any changes however which occur in temperature across thewidth of the strip make it impossible to produce good metal strip.

It has been found that the temperature can accurately be controlled bythe use in certain ways of controlled coolant which may be andpreferably is at the same time a lubricant. Certain features oflubricant control have been disclosed in the copending application ofmyself and John E. Eckert, Serial No. 477,087, filed February 25, 1943now Patent No. 2,566,679 and entitled Rolling Mills and LubricationMethods and Means Therefor. As set forth in that application one featureof successful lubrication is accomplished by causing even quantities oflubricant to escape through control clearances at the sides of the outerraces of the caster bearings. As shown in Figure 10, lubricant may bedelivered through bores 96 in the shafts 5 and in turn to the bearingsthrough holes 81 in the shafts and corresponding holes 82 in the innerraces 65 of caster bearings or the eccentric discs 6 which havehereinabove been described. The lubricant may otherwise be supplied tothe bearings, as through passageways in the mill housing means 40A toand through passageways in the saddles, thence to the s. afts and to thecaster bearings; but in any event the lubricant will be a coolant andwill be supplied undet sufiicicnt pressure to insure copious How tocarry away the heat. in Figure 10 clearances 54 are provided between thesaddles and the outer bearing races 8, and in case two bearings aremounted between each two saddles, there are also clearances 54A betweentheir outer races. In certain cases it is preferred to provide widerclearances and then fill them with loose rings 38 preferably made of orfaced with plastic compounds, because they may be easily changed to abigger or smaller clearance as desired.

As distinguished from types of mills in which a circulating oil bath wasmaintained in the hollow mill interior, being introduced at one side andwithdrawn at the other, the direct introduction of lubricant to thebearings has an advantage in that the outgoing oil prevents entry ofimpurities, especially metal chips, into the bearings.

Moreover, as also set forth in the copending application, Serial No.477,087, new Patent No. 2,566,679, in these improved mills the lubricantenters at or near the caster bearings, and flows therefrom to the hollowinterior of the mill, flowing toward the work piece from both sides, andis withdrawn from the mill at a level at or near the level of the workpiece or strip being rolled. The entire hollow interior of the mill maybe kept filled with a flowing body of the lubricant.

In the present instance, while it is preferred to maintain an oil bathin the lower half of the mill, it is sufficient in the upper half of themill to let the escaping lubricant cascade over the rolls of the upperhalf, thus lubricating and cooling them. This simplifies sealing of themill interior around the drive spindles. By letting the bulk of thelubricant out of the mill at the apertures provided for the strip, i. e.at the windows W in Figure 8, the strip is effectively cooled, and mostof the dirt carried by the strip is kept out of the mill. A practicalimprovement consists in providing bores 62 in Figures 2 and 4 at thelowermost portion of the mill housing, i. e. through the lower beam 48,to let out some of the lubricant, since this prevents dirt fromaccumulating there. Thus the mill becomes a completely self-cleaningmachine, providing the oil is properly filtered. Outside filtering andcooling means for the lubricant are provided but are not shown in thedrawings hereof.

The openings 62 will be located in such a way that oil may be drainedfrom them without reentering the caster bearings; and the quantity ofoil so drained may be controlled so as to maintain any desired oil levelin the lower part of the mill, and/or to drain from the lower part ofthe mill oil introduced into the caster bearings therein, and oilentering the lower half of the mill from the upper half around the edgesof the strip at the ends of the rolls.

Where either or both halves of the mill are kept filled with circulatingbaths of lubricant, a preferable wayof letting the lubricant out of themill is by providing a flexible strip-metal scraper 55 in Figure 4contacting the work roll 1 lengthwise close to the pass line. While onlyone such scraper has been shown, it will be clear a'r/ sss how otherscould be provided at the opposite side of the lower work roll and atboth sides of the upper work roll. This scraper or scrapers are held inholders 56; and these holders are preferably provided with spaced slotsor apertures 56A above the scrapers, through which apertures thelubricant may escape from the mill interior, flushing the side of thescraper orscrapers which faces the strip being rolled,

Whether or not scrapers are employed, a further greater advantage may besecured by flushing the rolls and work piece with high pressurelubricant supplied through a separate outside source through jetelements 57 in Figure 4 which are held in holders 66 which may be thesame as the holders for the scrapers. If scrapers are employed, thesejets of lubricant will flush the outsides of the scrapers also. The useof high pressure lubricant separately introduced in this positionprovides efiective cooling of the work rolls themselves by fluid jetsdirected into the bite of the rolls and impinging against that part ofthe roll surface which is just leaving or coming into contact with thestrip. It is known that high heat is generated'in the roll bite, and thework roll picks it up. The use of high pressure lubricant jets makes itpossible to evacuate this heat before it has had a chance to penetratemore deeply toward the interior of the roll body. While Figure 4illustrates jets 57 at but one side of the mill, it will be obviouswithout illustration that they can be provided at both sides of themill. The lubricant introduced by means of such jets will for the mostpart leave the mill through the windows W.

It is preferred to make the jets have a horizontal direction which isnot normal but slightly oblique to the roll axis, the jets situated tothe left of the center of the mill inclining toward the left, and thosesituated to the right of the center inclining toward the right, and ifnecessary increasing the inclination of the jets as they approach theends of the rolls. This gives to the escaping lubricant a certainacceleration away from the center of the mill, thus taking care ofdrainage of lubricant from the narrow space and insuring increasedturbulence. When sufliciently high oil pressures are used, such asseveral hundred pounds per square inch, better flushing and coolingresults are obtained if the jets are used alone, i. e. without thescrapers 55.

Also in Figure 4 there is illustrated a seal 60 held in a holder 66 forclosing the space between the walls and the throat of the housing. Thisseal is a resilient strip-like member contacting the periphery of anintermediate roll such as the roll 3A. If this seal is located on theside where the strip leaves the mill, it will be appreciated that thedirection of motion is such that the seal wipes a dry surface of theroll 3A, which makes its action very eflicient. Such seals may belocated at both sides of the mill and in both halves of the mill, forexample, contacting all rolls 3A and 38.

Such seals may be caused to perform several functions. In some instancesin rolling it is desirable to produce a perfectly dry strip, i. e. tohave a dry strip exit fro-m the work rolls without the use of wipingmeans contacting the strip directly.

Where seals 60 are used against the rolls 3A and 3B, it will be notedthat they have the effect of sealing lubricant into the hollow millinterior on the side of the strip at which they are used. If this isdone at the lower side of the mill, the lubricant introduced through thecaster bearings may be exhausted through the openings 62. If it is doneat the upper side of the mill, the lubricant introduced at the casterbearings may be otherwise exhausted as through lateral openings at bothsides of the mill, or through longitudinal passageways in the holders 66themselves, which passageways have lateral branches into the milldistributed in various ways across the mill width.

The use of seals 60 does not preclude the flushing of No. 477,087, nowPatent 2,566,679.

the strip with high pressure sprays where this is desired. For example,the nozzles 57 may be used along with the seals 60, and in this fashionthe coolant used against the strip may largely be kept separated fromthe oil which is employed as a coolant and lubricant in the mill proper.It will be noted also that when scrapers 55 are not used but seals 60are, and where these seals have a bearing against two of the outermostseries of intermediate rolls, the coolant and lubricant introducedthrough the nozzles 57 can contact not only the strip and surfaces ofthe work rolls 1 but also surfaces of the first intermediate rolls 2 andthe other intermediate rolls such as the series 3, 3A and 3B. Veryefiicient cooling can be had in this way by volumes of cooling fluidessentially separate from the fluid used to lubricate the mill parts. Inthe case of some metals it is vital for the rolling proces that thestrip be effectively cooled after each pass, and this is readilyaccomplished by providing other similar sprays upon the stripbothentering and leaving the mill, preferably within the throats or windows'of the housing but, if required, also outside of it.

Excepting in the case of the dry strip mentioned above, the strip as itleaves the mill will of course be covered with lubricant, and this inthe past has caused some difliculty together with loss of lubricant,until it was found that the lubricant can effectively be wiped from thestrip by applying against it a flexible hose 58 in Figure 4 supported bya metal bar extending across the window W so as to insure uniformpressure of the hose against the strip. A synthetic rubber hose withexternal flanging such as is used in gas welding gives satisfactoryresults. A metal rod 59 is preferably inserted within the hose toprevent it from collapsing.

In instances where it is desired to employ a lubricant for the casterbearings which is separate from the lubricant or coolant used elsewherein the mill or upon the strip, the construction shown in Figure 11 maybe adopted, as set forth in the said copending application, Serial Thisconsists in using bearings for the caster as at 7, having positivesealing means 63 so that a separate lubricant can be circulated throughthem continuously for lubricating and cooling purposes. In this instancethe lubricant can be introduced to the bearings through a longitudinalpassageway in the shaft 50, and withdrawn through another longitudinalpassageway 91, these passageways having cross connections to thebearings as shown, the flow of oil being indicated in Figure 11 byarrows. A passageway maybe formed in the mill housing means 40A tosupply lubricant around the casters but not to the bearings thereof,this latter lubricant being used to cool the interior of the mill andthe other elements contained therein such as the intermediate rolls andthe working rolls.

It is also possible to use in these mills suitably sealed bearings withgrease packing.

In the ways set forth separate roll lubricant and coolant can be used,which permits the use of a wide range of substances which might nototherwise be desirable for bearing lubrication.

Modifications may be made in my invention without departing from thespirit of it. Having thus described my invention in certain exemplaryembodiments, what I claim as new and desire to secure by Letters Patentis:

1. In a cold rolling mill having small diameter work rolls, beamsextending parallel to the axis of said rolls, said rolls being backed byintermediate rolls and casters which in turn are backed against saidbeams so as to give to said Work rolls support throughout theiroperating length, the combination of a Work roll having a slight crownand a cylindrical intermediate roll having a taper relief, the saidtaper starting inwardly of the strip edge and extending outwardly beyondsaid strip edge.

2. The structure claimed in claim 1 in which said inter- 11 mediate rollis so taper relieved at both ends, the nonrelieved central portion ofsaid roll being shorter than the width of the strip being rolled.

3. In a cold rolling mill having small diameter work rolls, end housingmembers including spaced upright columns, and beams extending across themill from one housing to the other parallel to the axes of said rolls,end portions of said beams forming portions of said end housing, saidWork rolls being backed by intermediate rolls, and said intermediaterolls being supported by casters which, in turn, are backed at spacedintervals against said beams so as to give said work rolls supportthroughout their operating length, said beams being tapered adjacenttheir ends so as to permit a greater deflection adjacent said housingswithout disturbing the tendency toward greater deflection at the centerof said mill, whereby to cause said deflections to be self-compensatingirrespective of specific loads, an intermediate roll for one of saidwork rolls having a taper relief at one end, and an intermediate rollfor the other of said Work rolls having a taper relief at its oppositeend, and means for adjusting the axial position of said taper relievedintermediate rolls at the start of a rolling operation whereby the saidtaper relieved portions of said intermediate rolls may be brought intocoincidence with edge portions of strips being rolled in the said mill,over a substantial range of differing Widths of strips.

References Cited in the file of this patent UNITED STATES PATENTS921,042 Williams May 11, 1909 1,772,248 Gibbons Aug. 5, 1930 1,895,607Coe Ian. 31, 1933 1,903,724 Rohn Apr. 11, 1933 2,047,883 Phillips July14, 1936 2,056,433 Matthews Oct. 6, 1936 2,085,449 Rohn June 29, 19372,140,289 Hurtt et al. Dec. 13, 1938 2,187,250 Sendzimir Jan. 16, 19402,236,460 Thomas Mar. 25, 1941 2,479,974 Sendzimir et al. Aug. 23, 1949FOREIGN PATENTS 670,382 Germany Dec. 22, 1938 Great Britain May 7,

